This invention relates in general to universal joints and in particular to an improved apparatus and method for retaining the bearing cups on the trunnions of a universal joint cross when supplying lubricant therein.
Universal joints are well known devices which provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joints are widely used to connect rotatable members in vehicle drive train systems. In a typical drive train system, a first universal joint is connected between an output shaft of an engine/transmission assembly and a first end of a driveshaft tube, while a second universal joint is connected between a second end of the driveshaft tube and an input shaft of an axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of misalignment between the rotational axes of these three shafts.
A typical structure for a universal joint includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups to permit relative rotational movement therebetween. The bearing cups mounted on a first opposed pair of the trunnions are connected to a first yoke which, in turn, is secured to one of the rotatable components of the vehicle drive train system. Similarly, the bearing cups mounted on a second opposed pair of the trunnions are connected to a second yoke which, in turn, is secured to a second one of the rotatable components of the vehicle drive train system.
Frequently, the first and second universal joints are manufactured concurrently with the driveshaft tube at a first location, then shipped as a unit to a second location for assembly with the other components of the vehicle drive train system. In such a manufacturing process, yokes are initially secured to the ends of the driveshaft tube, then a universal joint is connected to each of the yokes. Thus, for each of the universal joints, only one opposed pair of the bearing cups is connected to a yoke and, therefore, positively retained on the respective trunnions. The other opposed pair of the bearing cups remains mounted on the respective trunnions, but is not positively retained thereon. Following installation on the yokes, each of the universal joints is purged with lubricant. Such purging is well known in the art and involves the injection lubricant within the cross at a relatively high pressure. The lubricant passes through bores formed through each of the trunnions so as to move into the regions of the bearings disposed between the bearing cups and the trunnions.
Because of the high pressure conditions generated during the lubricant purging process, the bearing cups are urged to move radially outwardly from the ends of the respective trunnions. As mentioned above, the lubricant purging process typically occurs after the universal joints have been secured to the ends of the driveshaft tube. Thus, as mentioned above, only one opposed pair of the bearing cups is positively retained on the trunnions of each of the universal joints during the purging process. The other opposed pair of the bearing cups must be positively retained on the trunnions of each of the universal joints by other means during the purging process. A number of structures are known in the art for retaining these bearing cups on the trunnions. However, it has been found that known retaining structures are difficult to install and remove in an efficient manner. Thus, it would be desirable to provide an improved apparatus and method for retaining the bearing cups on the trunnions of a universal joint cross when supplying lubricant therein.